Cops have hit another brick wall in a vexing 30-year mystery that saw B.C. family drop off the face of the earth.

Around 1:21 a.m. on Aug. 2, 1989, Ronald Jack, his wife Doreen and their two children Russell, 9, and Ryan, 4 went missing.

RCMP say detectives are treating the disappearance as a homicide until they learn differently.

In August, a portion of the Saik’uz First Nation reserve — near Prince George — was searched as investigators looked for new clues that might finally unearth what happened.

“And then there was nothing found. That was very disappointing to me,” Doreen’s sister Marlene Jack told CBC News.

“Now all I care about is to bring my family home, that’s it. The justice part is up to the RCMP if they’re willing to pursue it.”

The mystery of the Jack family began on Aug. 1, 1989.

Ronald Jack met a man at his local watering hole, the First Litre Pub, four blocks from the family home.

The white male offered them jobs at a logging camp that was reportedly near Clucluz Lake — also offering daycare services for their children, the mystery man said.

Ronald Jack told his parents they were going to work in the bush at the camp. They would be back in 10 days, so their son Russell could start school.

Do you know this man? He is suspected in the disappearance of the Jack family in 1989. RCMP

In the early morning hours, they left with the unknown male in a dark-coloured 4×4 pickup truck.

They were reported missing Aug. 25, 1989.

In the intervening decades, cops conducted hundreds of interviews, searched homes and scoured the bush looking for any trace of the family.

Not a single clue was left behind.

“I want to thank everyone who helped with the search for their support, even though there was nothing found,” Marlene Jack told reporters.

“I would like to ask from the bottom of my heart that everyone with information come forward to police. Please help bring our family home.”

Cops say the mystery man — as described in 1989 — is a white male, 35-40 years old, 6-foot to 6-foot-6 in height with reddish-brown hair, a full beard and wearing a baseball cap, red checkered work shirt, faded jeans, blue nylon jacket, and work boots with leather fringes over the toes.

Anyone with information on the incidents is asked to call Prince George RCMP at 250-561-3300 or anonymously contact Crime Stoppers at 1-800-222-8477 or www.pgcrimestoppers.bc.ca.